A PR21 spokeswoman said the agency had come to the end of its one-year contract.

Conduit is not replacing the agency. Instead, all press enquiries are being handled by the company’s Irish PR agency , White & Associates.

Conduit has struggled for market share despite offering consumers the cheapest call rates and having the biggest marketing budget.

However, from 1 November, it reneged on its low-cost positioning of 20p a minute by introducing an additional 25p connection charge, bringing it in line with its competitors.

PR21 spearheaded the company’s efforts to position 11 88 88 as a cheaper alternative to rivals, particularly BT. The agency is understood to have been responsible for prompting media coverage of BT’s controversial plans to outsource its directory enquiries call centre to India.